Here is an example of a cam latch. I'd spend sometime poking around on the net. GW used a lot of Southco items in the past - still do. You may not find the same one, but should be able to find something that works. https://www.silver.com.tw/upload_files/a-lock-accessories/A050.jpg
Here are your hinges....
Southco E6-10-301-20 Series Adjustable Torque Position Control Hinge with Holes, Acetal Copolymer, 1.69" Leaf Height, 6.99 in-lbf Symmetric Torque, Black, Pack of 1
From the web...
toner E302 Rocket Release is extremely versatile, it is considered to be the “most paintable” release agent available when molding plastics and similar materials. Provides a long lasting anti-stick film for fast, easy part removal from molds and multiple part releases per...
I'd say pre 2004 are at highest risk. 2016 and up the lowest. In the middle, gotta pay attention to coring in bigger beams, wood on decks and hatches, transom and stringers.
First check if salt or freshwater and see how the water is getting in.
I'd consider putting in drain holes in the specific area. Will need to glass and I'd gel coat as an added measure. Best to do on the hard when dry.